Electrical switch having means for interconnecting concentric switch shafts



June 1, 1965 M. D. BUTLER ETAL 3,137,118

ELECTRICAL SWITCH HAVING' MEANS FOR INTERCONNECTING CONCENTRIC SWITCH SHAFTS Filed Jan. 18, 1962 VARIABLE mi i 6 /NvEA/rons. MARLow a BUTLER oswALo c. svEHAuG 5y F Ig 5 BucKHoR/v, CHEATHAM a BLoRE AT TORNE YS United States Patent O 3,187,118 ELECTRICAL SWITCH HAVING MEANS FGR INTERCONNECTNG CGNCENTRlC SWTCH SHAFTS Marlow D. Butler, Hillsboro, and Oswald C. Svehaug, Portland, Greg., assignors to Tektronix, line., Beaverton, Greg., a corporation of Oregon Filed Jan. 18, 1962, Ser. No. 167,117 7 Claims. (Cl. 200-5) The subject matter of the present `invention relates generally to electrical switches and in particular to an electrical switch assembly having at least two switch devices which can be operated together or independently to change the electrical connections of the switch contacts in such switch devices by rotational and longitudinal movements of a knob device in such switch assembly.

The electrical switch of the present invention is especially useful when mounted on the control panel of a test instrument, such as a cathode ray oscilloscope, so that it can be employed, for example, to vary the horizontal sweep rate of such oscilloscope and to select one or both of two possible horizontal sweep signal generators for the sweep signal applied to the horizontal deflection plates of such oscilloscope. However, the electrical switch herein disclosed may be used in any environment where it is desirable to have a compact multiple function switch which is simple in construction and in operation.

Briefly, one embodiment of the electrical switch assembly of the present invention may employ a pair of switch shafts coaxially supported, with the rst of such shafts having a hollow tubular shape and the second of such shafts being mounted for rotation inside of such first shaft. A plurality of switch devices each having a rotatable contact member and a stationary contact member are positioned relative to the shafts so that at least one of such switch devices is actuated by the first shaft and at least one other of such switch devices is actuated by such second shaft. Thus, the rotatable contact members of such switch devices are rotated by such switch shafts to change the electrical connections of the switch contacts in such switch devices. A knob device is provided and normally connects the lirst shaft with the second shaft for rotation of both shafts by such knob device to operate the switch assembly as a gang switch. The shafts can be disconnected from each other by longitudinal movement of such knob device so that each of such shafts can be positioned independently of the other in order to operate the switch assembly as two separate switches.

The knob device includes a rst switch position indicating member attached to such first shaft and a second switch position indicating member attached to such second shaft. A detent hole is provided in one of such indicating members and a spring biased detent pin is attached to the other of such indicating members so that the detent pin will engage the detent hole to interconnect the switch shafts when the indicating members are rotated with respect to each other into the gang switch position. The detent pin is removed from such detent hole to disconnect the switch shafts when such indicating members are moved longitudinally and rotated with respect to each other out of such gang switch position.

One of the objects of the present invention is to provide an improved electrical switch assembly which is compact and simple to operate.

Another object of the invention is to provide an improved electrical switch assembly for controlling a plurality of different electrical circuits which is simple and inexpensive in construction and also simple and reliable in operation.

Another object of the present invention is to provide ICC an electrical switch assembly in which a pair of coaxially supported switch shafts are employed with one of said shafts being mounted for rotation inside such other shaft, along with at least one switch device having a rotatable contact member and a stationary contact member attached to each of such switch shafts, and a knob device for interconnecting such switch shafts by rotation of such knob device so that both of such shafts can rotate together in order to operate such switch assembly as a gang switch, and for disconnecting such switch shafts from each other by longitudinal movement and rotation of such knob device so that such shafts can rotate independently from each other in order to operate such switch assembly as two separate switches to provide a compact multifunction electrical switch which is simple and reliable in operation.

A still further object of the present invention is to provide an improved electrical switch assembly in which at least two switch devices are employed along with a control device for interconnecting such switch devices by a detent member so that such switch assembly operates as a gang switch and for disconnecting such switch devices from each other by disengaging such detent member so that such switch assembly can operate as two separate switches to provide a compact electrical switch assembly which can be operated either as a gangl switch or as two separate switches by longitudinal movement and rotation of a single switch knob.

Additional objects and advantages of the present invention will be apparent from the following detailed description of preferred embodiments thereof shown in the attached drawings of which:

FIG. 1 is a side elevation of an electrical switch assembly in accordance with the preferred embodiment of the present invention;

FIG. 2 is a front view of the electrical switch assembly of FIG. l as viewed from the line 2-2 of FIG. l;

FIG. 3 is a vertical section view taken on the line 3 3 of FIG. 1;

FIG. 4 is a vertical section view taken on the line 4-4 of FIG. 2;

FIG. 5 is a horizontal section view taken on the line 5 5 of FIG. 2;

FIG. 6 is a vertical Section View taken on the line 6-6 of FIG. 4; and

FIG. 7 is a vertical section view taken on the line 7-7 of FIG. 4.

A preferred embodiment of the electrical switch assembly of the present invention shown in FIG. 1 includes a knob device lil, connected `to a first switch shaft 12, a second switch shaft 1d, and a third switch shaft 16. The first and second switch shafts 12 and 14 are of a hollow tubular construction while the third switch shaft 16 is in the form of a solid cylindrical rod so that the second and third shafts can rotate inside the first shaft and the third shaft can also rotate inside the second shaft. Each of these shafts actuate diferent switch devices and such switch devices may be of any type whose electrical connections can be controlled by the rotation of a switch shaft. In the example shown, a first switch device 18 is actuated by the rst switch shaft 12, a second switch device 20 is actuated by the second switch shaft 14 and a potentiometer 22 including a snap action switch is actuated by the third shaft 16. The switch and potentiometer 22 is connected to the shaft 16 by a connecting pin 24 inserted through a hole in the end of shaft 16 and inserted in a notch at the end of a shaft 26 forming part of the switch and potentiometer 22. The three switch shafts 12, 14 and 16 are supported in an L-shaped support bracket 28 by a sleeve member 30 in which the shaft 12 is journaled for rotation and also held against endwise movement with respect to such sleeve member.

anemie The sleeve member 3h has a screw-threaded end extending through the bracket 255. A nut 32 on such end secures the `sleeve member in position in the support bracket. The support bracket 2S is mounted on an instrument chassis by means of a pair of nut, bolt and lock washer assemblies 34 so that the switch shafts extend through an opening 36 in the control panel 38 of the instrument and are connected to the knob device il@ on the front of such panel.

Each of the switch devices lit, 2d and 22 is secured to a pair of support rods du extending parallel to the switch shafts and equally spaced from opposite sides thereof. The switch and potentiometer 22 is attached to such support rods by a support plate 32 having a central opening through which an externally threaded bearing sleeve i3 for `the potentiometer shaft 2o extends. rlfhe sleeve 43 is secured to the support plate by a nut and lock washer assembly de. The plate 42 has a pair of support rod openings which enable attachment of such support plate to the support rods 4@ by an attaching structure including a pair of nut and lock washer assemblies do. The attaching structure also includes a first pair of spacer sleeves/i8 positioned upon the support rods 4@ between the support plate i2 and an alignment plate 5h. ri`he alignment plate has a central aperture through which the second and third switch shafts M and le extend and also has a pair of support rod holes through which support rods 4t) extend. The shaft la is journaled in the alignment plate so that the switch shafts 14'. and fio are held in alignment with the switch device Ztl and with the potentiometer shaft 26. A second pair of spacer sleeves 52 on the support rods d@ between the plate 5h and the switch device 2@ accurately positions the switch device 2h withrespect to alignment plate Sh.

As shown in FIG. 3, each switch device l and 2h includes an outer annular stationary contact member '54 supported by the support shafts liti. Thus, each contact member 54 has holes in the opposite sides thereof fitting the support rods. The shafts 12. and M- have flattened sides and each switch device includes an inner rotatable contact member 56 in the form of a circular insulating plate having a central opening fitting one of the shafts 12 and 14.'- so as to be keyed thereto. The stationary contact member 54 of each switch device is in the form of a plate of insulating material having a plurality of spaced contacts 58 mounted thereon for engagement with one of two rotatable switch contacts dii mounted on opposite sides of the insulating plate of the rotatable contact member 56 and positioned to hold the rotary contact member with the stationary contact member. Rotation of the switch contact 60 changes the electrical connection of the switch contacts 58 by their engagement with a switch contact projection 62 on rotary contact 60.

Since both switch devices i8 and 2@ are step switches, a step detent mechanism is connected to each of their associated switch shafts i2 and lli. rThe first step detent mechanism includes an annular detent plate 64 having a plurality of detent holes around the periphery thereof. A detent member 6o including a spring arm and a ballbea'ring :detent is journaled in the detent plate 64 and has a central opening fitting the switch shaft l2 for rotation therewith. The detent plate 64 is supported by and held stationary by support rods iti which extend through a pair of holes in the opposite sides of such detent plate. A pair of nuts 68 on the support rods hold the detent plate on such rods. A second detent mechanism similar to the abovevdeseribed first .detent mechanism has a detent member 7d with a central opening fitting the switch shaft 14. Such detent member is journaled in a detent plate 72 supported on the support rods 4h. The detent plate '72 is accurately spaced from switch plates 2d by a third pair of spacer sleeves 74 on the rods iii and from switch plates i@ by a fourth pair of spacer sleeves '76. The detent plate diis accurately spaced from switch plates i3 by a fifth pair of spacer sleeves 7 3.

The knob device l@ `of FIG. 1 is shown in greater detail in FIGS. 2 and 4 to 7. it includes an inner dial member d@ made of transparent plastic material having a pair of switch position index markers S2 on the under surface thereof with a detent hole S4 in the outer surface of such dial member. The inner dial member d@ is mounted on one end of the first switch shaft l2 and secured thereto by means of a setscrew do extending through a hub portion of such dial member which may be provided with a metal sleeve insert Si; for increased strength. Another dial device including an annular member 9i! of plastic or other suitable material and a metal bushing member 92 is mounted on one end of the second switch shaft id. The bushing member 92 is secured to the shaft il@ by a setscrew 94E- extending through such bushing. A sliding keyway element 96 on the inner surface of such knob member connects the knob member to the bushing for axial sliding movement of the knob member on the bushing. The knob member 9@ is provided with a plastic pointer element 9d (PEG. 2) for indicating the angular position of such knob member and shaft la rotated by such knob member through the bushing member 92. A clearance hole Miti (FlG. 4) is provided through the side of the knob member for access lto the setscrew 94. Three axially extending, circumferentially spaced, cylindrical shaped cavities N2 are provided in the knob member 9d. A coiled spring lliifi is positioned in each of the cavities liti?. so that one end of each of such springs extends into contact with the under surface of a radially extending flange MP3 on the outer end of the bushing 92. A detent pin M6 is positioned within one of the cavities M2 and has a projecting end which extends through a passageway in the knob member 9h. Such end of the pin Een enters a detent hoie Se in dial member d@ when the switch is in the position shown in FIG. 4. This detent pin is provided with an intermediate shoulder portion which is engaged by one of lthe coiled springs fihi and which engages the bottom of a cavity liliZ in the switch position shown. The knob member 9@ can be moved to the right in FIG. 4 to withdraw the end of the pin M6 from the detent hole d4 and such knob member can then be rotated independently of the dial member Sti.

A second dial knob idg of plastic or other material having a metal insert if@ is attached to the third switch shaft lid by a setscrew M2 extending through such knob and such insert. The dial knob ldd is positioned in contact with the exterior surface of the flange w3 of the bushing 92 and has a diameter less than the inside cli-- ameter of the outer portion of the knob member 9@ to provide a clearance for such knob member in order that it may slide longitudinally along keyway 9o parallel to the axis of the three switch shafts. Thus, the knob member 9d may be moved to the right `from switch position shown in FIG. 4 and in the direction of arrows llllli so that it can be rotated clockwise or eounterclockwise as indicated by arrows die in FIG. 2 until detent pin M26 is disengaged from detent hole Switch shafts i2 and lid are thus disconnected from each other thereby enabling switch device 2d to be operated independently of switch device lid upon further rotation of knob member 9h. The switch shaft Elli can thus be rotated independently of switch shaft i2 so that switch devices iii and 2@ function as two separate independent switches. The pin like rests on the outer surface of the dial Sti during such independent rotation but any time the knob member Mi returns to the position relative to dial titi shown in FIG. 4, the switch shafts i2 and M are interconnected by means of detent pin iid@ and detent hole Siso that such switch shafts rotate together and switch devices 13 and 2@ function as a gang switch.

As it has been previously indicated the electrical switch assembly of the present invention mayffor example, be used to control the horizontal sweep rates of a cathode ray oscilloscope and to select one or both of a pair of different sweep generators employed in such oscilloscope so that a time per centimeter index number appearing in the window formed by index markers 82 on dial member 80 indicates the sweep rate of one of the sweep generators and the pointer element 98 on knob member 90 indicates the sweep rate of the other sweep generator. In the gang switch position shown in FIG. 2 the horizontal sweep rates of the two sweep generators are the same and as indicated are 50 microseconds per centimeter. However, in the unganged positions of detent pin lilo and detent hole 84 the two sweep generators may be operated at different sweep rates so that pointer 98 is at a different setting of the time per centimeter scale on control panel 3S than index markers 82. The function of the snap action switch and potentiometer 22 is to allow a continuously variable sweep rate for one of the sweep generators to be controlled by rotating the knob 108 between a calibrated position Where the potentiometer is switched off and a maximum uncalibrated position, indicated by the index mark 11S on such knob. Previous cathode ray Oscilloscopes have required a separate electrical switch assembly for each horizontal sweep generator so that the surface area occupied on the control panel by the previous switches was approximately twice that of the electrical switch assembly of the present invention. The present electrical switch assembly by requiring less surface area on the control panel allows additional front panel controls to be ernployed in the oscilloscope so that it is a more versatile instrument.

It will be obvious that various changes can be made in the details of the present invention without departing from the spirit of the invention. Thus, the switch and potentiometer 22 and its associated switch shaft 16 and dial knob 168 may be eliminated without effecting the operability of the remaining switch assembly. Also, the electrical switch assembly of the present invention may be used to control other electrical functions than the horizontal sweep rate of a cathode ray oscilloscope. The scope of the present invention should therefore be de termined only by the following claims.

We claim:

1. An electrical switch assembly, comprising:

a pair of switch shafts coaxially supported with the first of said shafts having a hollow tubular shape and the second of said shafts being mounted for rotation inside said first shaft;

a plurality of switch plates each having a rotatable contact member and a stationary contact member;

means for connecting said switch plates to said shafts so that at least one of said switch plates is attached to said first shaft and at least one other of said switch plates is attached to said second shaft by their rotatable contact members for rotation with said shafts to change the electrical connection of the switch contacts; and

knob means for connecting said first shaft to said second shaft by rotation of one portion of said knob means so that both of said shafts can rotate together in order to operate said switch assembly as a gang switch, and for disconnecting said shafts from each other by movement parallel to the axis of said shafts and rotation of said portion of said knob means so that each of said shafts can rotate independently from the other in order to operate said switch assembly as two separate switches, said knob means including a spring biased detent member supported for longitudinal movement with said one portion of said knob means.

2. An electrical switch assembly, comprising:

a pair of switch shafts coaxially supported with the first of said shafts having a hollow tubular shape and the second of said shafts being mounted for rotation inside said first shaft;

a plurality of switch devices each having a rotatable Contact member and a stationary contact member;

means for connecting said switch devices to said shafts so that at least one of sai-d switch devices is attached to said first shaft and at least one other of said switch devices is attached to said second shaft in such a manner that the rotatable contact members of said switch devices rotate with said shafts to change the electrical connections of the switch contacts;

a first switch position indicating member attached to said rst shaft; and

a second switch position indicating member attached to said second shaft, with a detent hole in one of said indicating members and a detent supported for longitudinal movement with the other of said indicating members; and

means for rotating said indicating members with respect to each other so that said detent will engage said detent hole to interconnect said switch shafts into the gang switch position, and for moving said indicating members away from each other so that said detent will be removed from said detent hole to disconnect said switch shafts when said indicating members are rotated with respect to each other out of said gang switch position.

3. An electrical switch assembly, comprising:

a pair of switch shafts coaxially supported with the first of said shafts having a hollow tubular shape and the second of said shafts being mounted for rotation inside said first shaft;

a plurality of switch plates each having a rotatable contact member and a stationary contact member;

means for connecting said switch plates to said shafts so that at least one of said switch plates is attached to said first shaft and at least one other of said switch plates is attached to said second shaft in such a manner that the rotatable contact members of said switch plates rotate with said shafts to change the electrical connections of the switch contacts; and

knob means for interconnecting said first shaft with said second shaft by rotation of a portion of said knob means so that both of said shafts can rotate together in order to operate said switch assembly as a gang switch, and for disconnecting said shafts from each other by longitudinal movement along the axis of said shafts and rotation of said portion of said knob means so that each of said shafts can rotate independently from the other in order to operate said switch assembly as two separate switches,

sai knob means including a first switch position indieating member attached to said first shaft and a second switch position indicating member attached to said second shaft, with a detent hole in one of said indicating members and a spring biased detent supported for longitudinal movement and rotation with the other of said indicating members at a place so that said detent will engage said detent hole to interconnect said switch shafts when said indicating members are rotated with respect to each other into the gang switch position and said detent will be removed from said detent hole to disconnect said switch shafts when said other indicating member is moved longitudinally away from and rotated with respect to said one indicating member out of said gang switch position.

An electrical switch assembly for use in a cathode ray oscilloscope, comprising:

a pair of switch shafts coaxially supported with the first of said shafts having a hollow tubular shape and the second of said shafts being mounted for rotation inside said first shaft;

`a plurality of switch plates each having a rotatable contact member and a stationary contact member;

means for connecting said switch plates to said shafts so that at least one of said switch plates is attached to said first shaft and at least one other of said switch plates is attached to said second shaft by their rotatable contact members for rotation with aise/,11a

said shafts to change the electrical connections of said contact members; and

knob means for interconnecting said first shaft with said second shaft by rotating said knob means so that both of said shafts can rotate together in only one relative rotational position of said shafts in order to operate said switch assembly as a gang switch, and for disconnecting said shafts from each other by longitudinal movement and rotation of said knob means so that each of said shafts can rotate independently from the other in order to operate said switch assembly as two separate switches,

said knob means including a switch dial member attached to said first shaft and a switch knob member attached to said second shaft, with a detent hole in said dial member and a spring biased detent supported for longitudinal movement and rotation with said knob member at a place so that said detent will engage said detent hole to interconnect said switch shafts when said knob member is rotated with respect to said dial into the gang switch position and said detent will be removed from said detent hole Y to disconnect said switch shafts when said knob member is moved longitudinally along said shafts away from said dial member and rotated with respect to said dial member out of said gang switch position.

S. An electrical switch assembly, comprising:

a pair of switch shafts coaxiaily supported with the first of said shafts having a hollow tubular shape and the second of said shafts being mounted for rotation inside said said first shaft;

a plurality of switch mechanisms each having a rotatable contact member and a stationary contact member;

means lfor connecting said switch mechanisms to said shafts so that at least one of said switch mechanisms is attached to said first shaft and at least one other of said switch mechanisms is attached to said second shaft in such a manner that the rotatable contact members of said switch mechanisms rotates with said shafts to change the electrical connections of the contact members;

a first dial device including a dial member having a small end portion attached to said first switch shaft which extends through said small end portion for rotation of said first dial device with said first shaft, and a larger end portion having a detent hole in outer surface thereof and a switch position index thereon for indicating the rotational position of said first shaft;

a second dial device attached to said second switch shaft for rotation with said second shaft, said second dial device having a hollow knob member with an open-ended top portion and a partially closed bottom portion having a central opening through said bottom portion so that said second shaft extends through said central opening and a plurality of separate cavities in said bottom portion around said central openlng;

a plurality of springs positioned within said cavities of said knob member;

a detent member positioned within one of said cavities so that one end of said detent extends into a hole through the bottom of said one cavity and is held by the spring in said one cavity so that said one end of said pin can move between a first position ex- Y tending outward from the exterior surface of said knob member into said detent hole of said first dial device and a second position substantially even with said exterior surface; and

a bushing member having a small end portion extending through said central opening in said knob member and attached to said second shaft which extends into said small end portion of said bushing, said bushing also having a larger end portion which conforms to interior of said top portion of said knob and engages one end of said springs so that it is spaced from the bottom of said knob thereby and which is secured to said knob by a sliding key portion so that said bushing rotates with said knob and said knob may also be moved longitudinally along said bushing.

6. An electrical switch assembly, comprising:

a pair of switch shafts coaxially supported with the first of said shafts having a'hollow tubular shape and the second of said shafts being mounted for rotation inside said first shaft;

a plurality of switch plates each having a rotatable contact member and a stationary contact member;

means for connecting said switch plates to said shafts so that at least one of said switch plates is attached to said first shaft and at least one other of said switch plates is attached to said second shaft in such a manner that the rotatable contact members of said switch plates rotate with said shafts to change the electrical connections of the contact members;

a first dial device including a hollow cylindrical member having a small diameter end portion attached to said first switch shaft which extends through said small end portion for rotation of said rst dial de- Y vice with said rst shaft, and a larger diameter end portion having a detent hole in outer surface thereof and a switch position index thereon for indicating the rotational position of said first shaft;

a second dial device attached to said second switch shaft for rotation with said second shaft, said second dial device having a cup-shaped knob member with a central opening through the bottom thereof through which said second shaft extends and a plurality of separate cavities in said bottom of said knob member yaround said central opening;

a plurality of coil springs positioned with one of said springs within each of said cavities;

a detent pin positioned within one of said cavities so that one end of said pin extends into a hole through the bottom of said one cavity and is held by the spring in said one cavity so that said one end of said pin can move between a first position extending outward from the exterior surface of said knob member and a second position inward from said first position toward said exterior surface; and

a hollow cylinder bushing member having a small diameter end portion extending through said central opening in said knob member to a point adjacent said large end portion of said first dial device and attached to said second shaft which extends into said small end portion of said bushing, said bushing also having a larger diameter end portion which conforms to interior of the top of said knob member and engages one end of said springs so that it is spaced from the bottom of said knob thereby and which is secured to said knob by a sliding connection so that said bushing rotates with said knob and said knob may also be moved longitudinally along said bushing.

'7. An electrical switch assembly for a cathode ray oscilloscope, comprising:

a plurality of switch shafts coaxially supported with the first and second of said shafts having a hollow tubular shape, said second shaft being mounted for rotation inside said first shaft and a third shaft being mounted for rotation inside said second shaft;

a plurality of switch plates each having a rotatable contact member and a stationary contact member;

means for connecting said switch plates to said shafts so that a least one of said switch plates is attached to said first shaft and at least one other of said switch plates is attached to said second shaft by their roa variable resistance connected to said third switch shaft so that the value of said variable resistance may be changed by the rotation of said third shaft;

first dial device including a hollow cylindrical member having a small diameter end portion attached to said first switch shaft which extends through said small end portion for rotation of said first dial device with said first shaft, and a larger diameter end portion having a detent hole in outer surface thereof and a switch position index thereon for indicating the rotational position of said first shaft;

second dial device attached to said second switch shaft for rotation with said second shaft, said second dial device having a cup-shaped knob member with a central opening through the bottom thereof through which said second shaft extends and a plurality of separate cavities in said bottom of said knob member around said central opening;

a plurality of springs positioned within said cavities;

detent pin positioned within one of said cavities so that one end of said pin extends into a hole through the bottom of said one cavity and is held by the spring in said one cavity so that said one end of said pin can move between a first position extending outward from the exterior surface of said knob member and a second position substantially even with said exterior surface;

hollow cylindrical bushing member having a small diameter end portion extending through said central opening in said knob member to a point adjacent said large end portion of said first dial device and attached to said second shaft which extends into said small end portion of said bushing and said bushing also having a large diameter end portion which con- `forms to interior of the top of said knob member and engages one end of said springs so that it is spaced from the bottom of said knob member thereby and which is secured to said knob by a sliding key means so that said bushing rotates with said knob member but said knob member may be moved longitudinally along said bushing; and

a third dial device including a cylindrical knob element attached to said third switch shaft for rotation of said third shaft and supported adjacent the outer ysurface of said large end portion of said bushing, said knob element having an outer diameter which is less than the inner diameter of said knob member.

References Cited bythe Examiner UNITED STATES PATENTS 597,470 1/98 Norden 200-42 1,118,024 ll/ 14 Lawrence 200-5 1,579,215 4/26 Klosner 338-124 2,498,835 2/50 Brotman 74-504 X 2,561,348 7/51 Dunham 20G-33 2,642,503 6/ 5 3 Dietrich.

2,745,918 5/56 Stewart 200-36 2,976,377 3/61 Jordan 20G-38 3,023,388` k2/62 Di Girolamo et al 338-l7i2 FOREiGN PATENTS 592,944 2/ 34 Germany.

BERNARD A. GlLHEANY, Primary Examiner. 

1. AN ELECTRICAL SWITCH ASSEMBLY, COMPRISING: A PAIR OF SWITCH SHAFTS COAXIALLY SUPPORTED WITH THE FIRST OF SAID SHAFTS HAVING A HOLLOW TUBULAR SHAPE AND THE SECOND OF SAID SHAFTS BEING MOUNTED FOR ROTATION INSIDE SAID FIRST SHAFT; A PLURALITY OF SWITCH PLATES EACH HAVING A ROTATABLE CONTACT MEMBER AND A STATIONARY CONTACT MEMBER; MEANS FOR CONNECTING SAID SWITCH PLATES TO SAID SHAFTS SO THAT AT LEAST ONE OF SAID SWITCH PLATES IS ATTACHED TO SAID FIRST SHAFT AND AT LEAST ONE OTHER OF SAID SWITCH PLATES IS ATTACHED TO SAID SECOND SHAFT BY THEIR ROTATABLE CONTACT MEMBERS FOR ROTATION WITH SAID SHAFTS TO CHARGE THE ELECTRICAL CONNECTION OF THE SWITCH CONTACTS; AND KNOB MEANS FOR CONNECTING SAID FIRST SHAFT TO SAID SECOND SHAFT BY ROTATION OF ONE PORTION OF SAID KNOB MEANS SO THAT BOTH OF SAID SHAFTS CAN ROTATE TOGETHER IN ORDER TO OPERATE SAID SWITCH ASSEMBLY AS A GANG SWITCH, AND FOR DISCONNECTING SAID SHAFTS FROM EACH OTHER BY MOVEMENT PARALLEL TO THE AXIS OF SAID SHAFTS AND ROTATION OF SAID PORTION OF SAID KNOB MEANS SO THAT EACH OF SAID SHAFTS CAN ROTATE INDEPENDENTLY FROM THE OTHER IN ORDER TO OPERATE SAID SWITCH ASSEMBLY AS TWO SEPARATE SWITCHES, SAID KNOB MEANS INCLUDING A SPRING BIASED DETENT MEMBER SUPPORTED FOR LONGITUDINAL MOVEMENT WITH SAID ONE PORTION OF SAID KNOB MEANS. 